activate unschedulable pods only if the node became more schedulable

pkg/scheduler/internal/queue/scheduling_queue.go

@@ -71,6 +71,8 @@ type SchedulingQueue interface {
 	Close()
 	// DeleteNominatedPodIfExists deletes nominatedPod from internal cache
 	DeleteNominatedPodIfExists(pod *v1.Pod)
+	// NumUnschedulablePods returns the number of unschedulable pods exist in the SchedulingQueue.
+	NumUnschedulablePods() int
 }
 
 // NewSchedulingQueue initializes a new scheduling queue. If pod priority is
@@ -164,6 +166,11 @@ func (f *FIFO) Close() {
 // DeleteNominatedPodIfExists does nothing in FIFO.
 func (f *FIFO) DeleteNominatedPodIfExists(pod *v1.Pod) {}
 
+// NumUnschedulablePods returns the number of unschedulable pods exist in the SchedulingQueue.
+func (f *FIFO) NumUnschedulablePods() int {
+	return 0
+}
+
 // NewFIFO creates a FIFO object.
 func NewFIFO() *FIFO {
 	return &FIFO{FIFO: cache.NewFIFO(cache.MetaNamespaceKeyFunc)}
@@ -701,6 +708,13 @@ func (p *PriorityQueue) podsCompareBackoffCompleted(p1, p2 interface{}) bool {
 	return bo1.Before(bo2)
 }
 
+// NumUnschedulablePods returns the number of unschedulable pods exist in the SchedulingQueue.
+func (p *PriorityQueue) NumUnschedulablePods() int {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+	return len(p.unschedulableQ.pods)
+}
+
 // UnschedulablePodsMap holds pods that cannot be scheduled. This data structure
 // is used to implement unschedulableQ.
 type UnschedulablePodsMap struct {